Adding basic API.
Adding a basic eunit test.
Adding a basic URI parser to describe a backend:

It basically boils down to:
  cfkv:<backend>:<options>

with:
  - cfkv is the contant part, so don't change that
  - <backend> is a name defined in the application env mapping a backend module
    example: [backends, {<<"foo">>, cfkv_foo}]
             which defines the backend name "foo" using the module cfkv_foo
  - <options> is an optional part. Each option is a key/value pair. It's using
    the following syntax:
    <key>=<value>&<key>=<value> e.g.: foo=2&bar=[1,3]
    Those options depends of the backend implementation.